Revesz group reported a process for the production of 3-amino-5-fluoro-4-oxopentanoic acid derivative which is well known in the art to play an important role in caspase inhibitor (Revesz et al., Tetrahedron Lett. 1994, 35, 9693). However, this process used an intermediate 2-fluoroacetaldehyde that is volatile, and its aldol reaction requires a large amount of organic solvent. Moreover, the purification of the product is difficult since there is no intermediate obtained as the form of solid. To overcome these problems, the present inventors developed a process of Reaction Scheme 1 for preparing the compound of formula 1 which is practical and provides good yield (see: KR 10-2005-016203).

Although significant improvement was made compared to the Revesz's process, there is still room for further refinements in removing a very low temperature condition in preparing a compound of formula 2 by condensation between lithium anion of trimethylsilyl acetylene and ethylfluoroacetate, and in preparing a compound of formula 5 by condensation between anion of a compound of formula 4 and ethyl chloroformate (−25° C.˜−65° C., and below −40° C., respectively). Furthermore, the intermediates obtained from the above Reaction Scheme could not be purified easily, and so the above method was difficult to be used for synthesizing the compounds in a large scale. Therefore, there has been a need for a new method which does not require the very low temperature condition, and has an easy purification process.